Supports sending both regular and action %lin messages, using the
optional @ prefix.
Now transforms on-urbit URLs into arvo:// URLs prior to sending,
as opposed to on-render.
Unfortunately, the type hall uses for URLs doesn't support non-HTTP
protocols yet, so we send arvo:// URLs as %lin messages for now.
Input field gets styled based on detected message type. Italics for
action lins, underline for URLs.
Renders messages based on their speech type, as opposed to interpreting
%lin speeches and ignoring all others.
Italicizes %lin "@" messages.
Makes images clickable to open in new window.
